© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—6-1

Network Environment Management

Managing Router Startup and Configuration

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—6-2

Router Power-On Boot Sequence

1. Perform power-on self-test (POST).2. Load and run bootstrap code.3. Find the Cisco IOS Software.4. Load the Cisco IOS Software.5. Find the configuration.6. Load the configuration.7. Run the configured Cisco IOS Software.

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—6-3

Router Internal Components

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—6-4

ROM Functions

Contains microcode for basic functions

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—6-5

Finding the Cisco IOS Image

Order of search:1. Checks configuration register 2. Parses configuration for boot system command3. Defaults to first file in flash memory4. Attempts to boot from network server5. Boot helper image6. ROMMON

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—6-6

Loading the Cisco IOS Image from Flash Memory

The flash memory file is loaded into RAM.

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—6-7

Loading the Configuration

Load and execute the configuration from NVRAM If no configuration is present in NVRAM, enter setup mode

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—6-8

Displays the current and saved configuration

show running-config and show startup-config Commands

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—6-9

Determining the Current Configuration Register Value

Cisco IOS Software, 2800 Software (C2800NM-IPBASE-M), Version 12.4(5a), RELEASE SOFTWARE (fc3)Technical Support: http://www.cisco.com/techsupportCopyright (c) 1986-2006 by Cisco Systems, Inc.Compiled Sat 14-Jan-06 03:19 by alnguyen

ROM: System Bootstrap, Version 12.4(1r) [hqluong 1r], RELEASE SOFTWARE (fc1)

RouterX uptime is 1 week, 5 days, 21 hours, 30 minutesSystem returned to ROM by reload at 23:04:40 UTC Tue Mar 13 2007System image file is "flash:c2800nm-ipbase-mz.124-5a.bin"

Cisco 2811 (revision 53.51) with 251904K/10240K bytes of memory.Processor board ID FTX1013A1DJ2 FastEthernet interfaces2 Serial(sync/async) interfacesDRAM configuration is 64 bits wide with parity enabled.239K bytes of non-volatile configuration memory.62720K bytes of ATA CompactFlash (Read/Write)

Configuration register is 0x2102

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—6-10

Configuration Register Values

Configuration register bits 3, 2, 1, and 0 set boot option

Check the configuration register value with the show version command

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—6-11

Router Startup Flowchart

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—6-12

show version CommandCisco IOS Software, 2800 Software (C2800NM-IPBASE-M), Version 12.4(5a), RELEASE SOFTWARE (fc3)Technical Support: http://www.cisco.com/techsupportCopyright (c) 1986-2006 by Cisco Systems, Inc.Compiled Sat 14-Jan-06 03:19 by alnguyen

ROM: System Bootstrap, Version 12.4(1r) [hqluong 1r], RELEASE SOFTWARE (fc1)

RouterX uptime is 1 week, 5 days, 21 hours, 30 minutesSystem returned to ROM by reload at 23:04:40 UTC Tue Mar 13 2007System image file is "flash:c2800nm-ipbase-mz.124-5a.bin"

Cisco 2811 (revision 53.51) with 251904K/10240K bytes of memory.Processor board ID FTX1013A1DJ2 FastEthernet interfaces2 Serial(sync/async) interfacesDRAM configuration is 64 bits wide with parity enabled.239K bytes of non-volatile configuration memory.62720K bytes of ATA CompactFlash (Read/Write)

Configuration register is 0x2102 (will be 2142 at next reload)

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—6-13

show flash Command

RouterX#sh flash-#- --length-- -----date/time------ path1 14951648 Feb 22 2007 21:38:56 +00:00 c2800nm-ipbase-mz.124-5a.bin2 1823 Dec 14 2006 08:24:54 +00:00 sdmconfig-2811.cfg3 4734464 Dec 14 2006 08:25:24 +00:00 sdm.tar4 833024 Dec 14 2006 08:25:38 +00:00 es.tar5 1052160 Dec 14 2006 08:25:54 +00:00 common.tar6 1038 Dec 14 2006 08:26:08 +00:00 home.shtml7 102400 Dec 14 2006 08:26:22 +00:00 home.tar8 491213 Dec 14 2006 08:26:40 +00:00 128MB.sdf

41836544 bytes available (22179840 bytes used)

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—6-14

Summary

When a router boots, it performs tests, finds, and loads software, finds and loads configurations, and finally runs the software.

The major internal components of a router include RAM, ROM, flash memory, NVRAM, and the configuration register.

When a router boots, it searches for the Cisco IOS Software image in a specific sequence: location specified in the configuration register, flash memory, a TFTP server, and ROM.

The configuration register includes boot information specifying where to locate the Cisco IOS Software image. The register can be examined with a show command and change the register value with the config-register global configuration command.

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—6-15